Harden platform security, reliability, and CI after full audit.

Close deployment IDOR and gate stub payment endpoints, add production
secret validation, health probes, Redis-backed build progress, GitHub
Actions CI, expanded tests, billing/k8s refactors, and ops runbooks.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/eslint.config.mjs

@@ -0,0 +1,28 @@
+import tsPlugin from '@typescript-eslint/eslint-plugin';
+import tsParser from '@typescript-eslint/parser';
+
+/** @type {import('eslint').Linter.Config[]} */
+export default [
+  {
+    ignores: ['dist/**', 'node_modules/**', 'coverage/**'],
+  },
+  {
+    files: ['src/**/*.ts', 'test/**/*.ts'],
+    languageOptions: {
+      parser: tsParser,
+      parserOptions: {
+        ecmaVersion: 'latest',
+        sourceType: 'module',
+      },
+    },
+    plugins: {
+      '@typescript-eslint': tsPlugin,
+    },
+    rules: {
+      ...tsPlugin.configs.recommended.rules,
+      '@typescript-eslint/no-explicit-any': 'off',
+      '@typescript-eslint/no-require-imports': 'off',
+      '@typescript-eslint/no-unused-vars': ['warn', { argsIgnorePattern: '^_' }],
+    },
+  },
+];